Building a Cardboard Planetarium

Russell Eveleigh
Mar 8 · 4 min read

One trip down a YouTube rabbit hole I stumbled across the ingenious Beals Science Cardboard Planetarium, a geodesic cardboard dome big enough to fit an entire secondary school classroom inside. I thought having a go at making my own scaled down version would be a perfect lockdown project.

Geodesic Domes

Pentagon and hexagon made out of triangles
Pentagon and hexagon made out of triangles
Pentagon and hexagon formed from triangles.
net of a geodesic dome
net of a geodesic dome
The net of a geodesic dome.

My first exploration of geodesic domes used rolled up paper connected with split pins. And so it was I built a prison for my daughter!

Dome made out of straws.
Dome made out of straws.
Geodesic prison

I used the same technique to combine two hemispheres together to create an ‘Earth’ and ‘Sun’ to go along with the ‘Space’ theme in my classroom. The pupils loved helping. It was a genuine team effort as there were many head scratching moments.

Geodesic straw sphere
Geodesic straw sphere
The sun as a geodesic sphere

Cardboard Planetarium

The Beales Science project used 240cm by 120cm cardboard to create a dome that was 5m in diameter; I went for the largest dome I could create from A1 double walled cardboard, which turned out to be one with a diameter of 3m. I bought 100 sheets on eBay along with 300 12mm nylon screws to bind the pieces together.

A stack of double walled cardboard
A stack of double walled cardboard
65 out of a total of 100 sheets of double walled A1 white cardboard
12mm nylon bolts, M5 thread.

The dome element was made from 75 triangular pieces of cardboard and was given extra height by placing it on 15 rectangular pieces.

Dimensions of triangles for pentagons and triangles
Dimensions of triangles for pentagons and triangles
Dimensions of triangles for pentagons and triangles
Dimensions of rectangles which raise the dome
Dimensions of rectangles which raise the dome
Dimensions of rectangles which raise the dome

The plans above show how the pieces were put together. Not shown are the 3.7cm tabs along the edges of each shape. I drilled each tab in two places ready for the bolts.

It took most of the day to put up, but I was pretty pleased with the result.

My son stands in front of the dome with a metre stick for scale
From above
The dome in the evening
Cardboard dome with the moon and Venus visible in the sky
Cardboard dome with the moon and Venus visible in the sky
The Moon and Venus look on

The cardboard was white on one side so it would be ideal as a projector screen.

Inside of cardboard dome showing white walls.
Inside of cardboard dome showing white walls.
White side of cardboard ideal as a projector screen

I already had a cheap projector, but I bought a convex mirror hoping that it might curve the projected image somewhat. In fact, despite appearing entirely reflective, it seemed to somehow absorb the light as if it were a black cloth. Clearly more research (and money) is needed.

Mirror or light vacuum?

I discovered the ePlanatarium website which produces films specially formatted to suit curved surfaces. In the end though, Rio 2 was the film of choice to test out the set up, and, even as an unaltered projection, it worked well.

Projector propped up by cardboard
Projector propped up by cardboard
Even the projector props are made of cardboard
Rio 2 beat footage of the moon landing
Happy customers

I managed to dismantle it in 10 panels and hope that it will be much quicker to put up in future.

Parts

I enjoyed working on the project and my kids loved seeing how all the shapes came together. Hopefully, with fair weather it can stay in the garden for longer and it will last for a good while.

Age of Awareness

Medium’s largest publication dedicated to education reform | Listen to our podcast at aoapodcast.com

Age of Awareness

Stories providing creative, innovative, and sustainable changes to the ways we learn | Tune in at aoapodcast.com | Connecting 500k+ monthly readers with 1,200+ authors

Russell Eveleigh

Written by

A primary school teacher and family man in the UK who likes tinkering with code and who sometimes tries to write good.

Age of Awareness

Stories providing creative, innovative, and sustainable changes to the ways we learn | Tune in at aoapodcast.com | Connecting 500k+ monthly readers with 1,200+ authors